1. Field of the Invention
This invention relates generally to hot isostatic presses. More particularly, this invention relates to a hot isostatic pressing apparatus which is compact in construction and capable of performing hot isostatic pressing operations in an efficient and safe manner.
2. Description of Prior Art
Hot isostatic pressing (hereinafter referred to simply as "HIP") is known in the art as a technology which can simultaneously shape and sinter a powdery material in a high-pressure and high-temperature gas atmosphere. One of the advantages of HIP technology is that it prevents the coarsening of crystal grains due to excessive growth, thereby obtaining products having fine structure.
In HIP apparatus, it is necessary to transfer the material or product being formed into and out of a high pressure container in each cycle of operation. This transfer of the material or product being formed is now customarily performed using the procedures and apparatus illustrated in FIGS. 1(a) to 1(d) and FIG. 2.
Referring first to FIGS. 1(a) to 1(d), indicated at 1 is a high pressure container which is provided with an upper plug 2. A corresponding lower plug 3 is mounted on a lift member 6. The high pressure container 1 is internally provided with a heat insulator 4 and a heater (not shown). A material or product to be formed 9 placed on the lower plug 3 is loaded into and unloaded from the high pressure container 1 by upward and downward movements of the lift member 6 along posts 8. Subsequent to the preparatory stages shown in FIGS. 1(a) to 1(c), the high pressure container 1 is received in a center open space 5A of a rectangular holder frame 5. As shown in FIG. 1(d), the rectangular holder frame 5 contacts and presses against the upper and lower plugs 2 and 3. The rectangular holder frame 5 is mounted on a carriage 10 which is movable on rails 7. The frame 5 is used to reinforce lower ends of the high pressure container 1 against the upward and downward forces which act on the upper and lower plugs 2 and 3 during the HIP treatment, which takes place at high pressure and temperature. After a predetermined time period of HIP treatment, the carriage 10 is moved away from the high pressure container 1, and the now formed material or product 9 is taken out of the high pressure container 1.
Illustrated in FIG. 2 is a HIP apparatus including a high pressure container 11 mounted on a support frame 16. The upper and lower ends of the high pressure container 11 are closed with upper and lower plugs 12 and 14. Air-tightness of the closure is insured by means of seal blocks 12A and 14A, respectively. A heat insulator 15 and heating elements llA are provided to permit the processing of the materials or products to be performed under high-temperature and high-pressure conditions. The holder frame 5 is moved back and forth on a carriage 17 by a piston-cylinder 18. Indicated at 19 is a pusher carriage, at 20 is a pusher, and at 21 are rails for the pusher carriage 19.
In the conventional HIP apparatus shown in FIGS. 1 and 2, the holder frame 5 which is provided to withstand the upward and downward forces in the high pressure container 1 or 11 is transferred toward and away from the container at the time of loading and unloading the materials or products to be formed. Accordingly, the HIP apparatus as a whole is very heavy and needs a great deal of floor space for installation. Moreover, the convention HIP apparatus shown in FIGS. 1 and 2 suffers from the problem of low productivity due to the long cycle time of the HIP operation.
Furthermore, the conventional HIP apparatus which utlizes an ultra high pressure gas (i.e., on the order of about 2000 kg/cm.sup.2) is usually provided with surrounding partition walls in order to protect against prossible accidents. In the connection, it has been the usual practice for the manufacturers of the HIP apparatus to design the HIP apparatus itself separately from the protective partition walls, leaving the problem of construction of the protective partitition walls in the hands of the ultimate users of the apparatus. However, this arrangement has not been entirely satisfactory because the ultimate users of the HIP apparatus are frequently inexperienced in the construction of such walls.